The Experts below are selected from a list of 501 Experts worldwide ranked by ideXlab platform

Amir K. Khandani - One of the best experts on this subject based on the ideXlab platform.

  • Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
    2006 IEEE International Symposium on Information Theory, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, we show that there is an optimal codeword Length which maximizes the throughput. We examine the throughput of the conventional scheduling that transmits to the user with the maximum signal to noise ratio using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, a gap of Omega(radiclog log log K) exists between the achievable throughput and the maximum possible throughput of the system. We propose a simple scheduling that considers both the signal to noise ratio and the channel time variation. We show that by using this scheduling, the gap between the achievable throughput and the maximum throughput of the system approaches zero

  • ISIT - Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
    2006 IEEE International Symposium on Information Theory, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, we show that there is an optimal codeword Length which maximizes the throughput. We examine the throughput of the conventional scheduling that transmits to the user with the maximum signal to noise ratio using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, a gap of Omega(radiclog log log K) exists between the achievable throughput and the maximum possible throughput of the system. We propose a simple scheduling that considers both the signal to noise ratio and the channel time variation. We show that by using this scheduling, the gap between the achievable throughput and the maximum throughput of the system approaches zero

  • scheduling and codeword Length optimization in time varying wireless networks
    arXiv: Information Theory, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, it is shown that there is an optimal codeword Length which maximizes the throughput. The throughput of the conventional scheduling that transmits to the user with the maximum signal to noise ratio is examined using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, the gap between the achievable throughput and the maximum possible throughput of the system tends to infinity as K goes to infinity. A simple scheduling that considers both the signal to noise ratio and the channel time variation is proposed. It is shown that by using this scheduling, the gap between the achievable throughput and the maximum throughput of the system approaches zero.

  • Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
    2006 40th Annual Conference on Information Sciences and Systems, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, we show that there is an optimal codeword Length which maximizes the throughput. We examine the throughput of conventional scheduling that transmits to the user with the maximum signal to noise ratio using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, a gap of Omega(radiclog log log K) exists between the achievable throughput and the maximum possible throughput of the system. We propose a simple scheduling that considers both the signal to noise ratio and the channel time variation. In this case, among users which their fading gain is above a threshold, user that has minimum channel time variation is selected. We show that by using this scheduling, the gap between the achievable throughput and maximum throughput of the system approaches o(1).

Lajos Hanzo - One of the best experts on this subject based on the ideXlab platform.

  • Iteratively Decoded Variable Length Space-Time Coded Modulation
    2020
    Co-Authors: Soon Xin Ng, Lajos Hanzo
    Abstract:

    An Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Nonbinary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discretevalued source symbols are first encoded into variable-Length Codewords that are mapped to the spatial and temporal domains. Then the variable-Length Codewords are interleaved and fed to the precoded modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme contriving source coding, channel coding, modulation and spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is more than 14 dB better than that of the Fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4.

  • iteratively decoded variable Length space time coded modulation code construction and convergence analysis
    IEEE Transactions on Wireless Communications, 2007
    Co-Authors: Soon Xin Ng, Jin Wang, Lieliang Yang, Lajos Hanzo
    Abstract:

    An iteratively decoded variable Length space time coded modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Non-binary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discrete-valued source symbols are first encoded into variable-Length Codewords that are mapped to the spatial and temporal domains. Then the variable-Length Codewords are interleaved and fed to the precoder assisted modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme combining source coding, channel coding, modulation as well as spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is about 14.6 dB better than that of the fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4

  • Near-Capacity Variable-Length Coding - Iteratively Decoded Variable Length Space-Time Coded Modulation: Code Construction and Convergence Analysis
    IEEE Transactions on Wireless Communications, 2007
    Co-Authors: Soon Xin Ng, Jin Wang, Lieliang Yang, Lajos Hanzo
    Abstract:

    An iteratively decoded variable Length space time coded modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Non-binary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discrete-valued source symbols are first encoded into variable-Length Codewords that are mapped to the spatial and temporal domains. Then the variable-Length Codewords are interleaved and fed to the precoder assisted modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme combining source coding, channel coding, modulation as well as spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is about 14.6 dB better than that of the fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4

Mehdi Ansari Sadrabadi - One of the best experts on this subject based on the ideXlab platform.

  • Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
    2006 IEEE International Symposium on Information Theory, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, we show that there is an optimal codeword Length which maximizes the throughput. We examine the throughput of the conventional scheduling that transmits to the user with the maximum signal to noise ratio using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, a gap of Omega(radiclog log log K) exists between the achievable throughput and the maximum possible throughput of the system. We propose a simple scheduling that considers both the signal to noise ratio and the channel time variation. We show that by using this scheduling, the gap between the achievable throughput and the maximum throughput of the system approaches zero

  • ISIT - Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
    2006 IEEE International Symposium on Information Theory, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, we show that there is an optimal codeword Length which maximizes the throughput. We examine the throughput of the conventional scheduling that transmits to the user with the maximum signal to noise ratio using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, a gap of Omega(radiclog log log K) exists between the achievable throughput and the maximum possible throughput of the system. We propose a simple scheduling that considers both the signal to noise ratio and the channel time variation. We show that by using this scheduling, the gap between the achievable throughput and the maximum throughput of the system approaches zero

  • scheduling and codeword Length optimization in time varying wireless networks
    arXiv: Information Theory, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, it is shown that there is an optimal codeword Length which maximizes the throughput. The throughput of the conventional scheduling that transmits to the user with the maximum signal to noise ratio is examined using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, the gap between the achievable throughput and the maximum possible throughput of the system tends to infinity as K goes to infinity. A simple scheduling that considers both the signal to noise ratio and the channel time variation is proposed. It is shown that by using this scheduling, the gap between the achievable throughput and the maximum throughput of the system approaches zero.

  • Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
    2006 40th Annual Conference on Information Sciences and Systems, 2006
    Co-Authors: Mehdi Ansari Sadrabadi, Alireza Bayesteh, Amir K. Khandani
    Abstract:

    In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at each receiver, while the statistical characteristics of the fading process and the fading gain at the beginning of each frame are known to the transmitter. By evaluating the random coding error exponent of the time-correlated fading channel, we show that there is an optimal codeword Length which maximizes the throughput. We examine the throughput of conventional scheduling that transmits to the user with the maximum signal to noise ratio using both fixed Length Codewords and variable Length Codewords. Although optimizing the codeword Length improves the performance, it is shown that using the conventional scheduling, a gap of Omega(radiclog log log K) exists between the achievable throughput and the maximum possible throughput of the system. We propose a simple scheduling that considers both the signal to noise ratio and the channel time variation. In this case, among users which their fading gain is above a threshold, user that has minimum channel time variation is selected. We show that by using this scheduling, the gap between the achievable throughput and maximum throughput of the system approaches o(1).

Soon Xin Ng - One of the best experts on this subject based on the ideXlab platform.

  • Iteratively Decoded Variable Length Space-Time Coded Modulation
    2020
    Co-Authors: Soon Xin Ng, Lajos Hanzo
    Abstract:

    An Iteratively Decoded Variable Length Space Time Coded Modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Nonbinary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discretevalued source symbols are first encoded into variable-Length Codewords that are mapped to the spatial and temporal domains. Then the variable-Length Codewords are interleaved and fed to the precoded modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme contriving source coding, channel coding, modulation and spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is more than 14 dB better than that of the Fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4.

  • iteratively decoded variable Length space time coded modulation code construction and convergence analysis
    IEEE Transactions on Wireless Communications, 2007
    Co-Authors: Soon Xin Ng, Jin Wang, Lieliang Yang, Lajos Hanzo
    Abstract:

    An iteratively decoded variable Length space time coded modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Non-binary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discrete-valued source symbols are first encoded into variable-Length Codewords that are mapped to the spatial and temporal domains. Then the variable-Length Codewords are interleaved and fed to the precoder assisted modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme combining source coding, channel coding, modulation as well as spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is about 14.6 dB better than that of the fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4

  • Near-Capacity Variable-Length Coding - Iteratively Decoded Variable Length Space-Time Coded Modulation: Code Construction and Convergence Analysis
    IEEE Transactions on Wireless Communications, 2007
    Co-Authors: Soon Xin Ng, Jin Wang, Lieliang Yang, Lajos Hanzo
    Abstract:

    An iteratively decoded variable Length space time coded modulation (VL-STCM-ID) scheme capable of simultaneously providing both coding and iteration gain as well as multiplexing and diversity gain is proposed. Non-binary unity-rate precoders are employed for assisting the iterative decoding of the VL-STCM-ID scheme. The discrete-valued source symbols are first encoded into variable-Length Codewords that are mapped to the spatial and temporal domains. Then the variable-Length Codewords are interleaved and fed to the precoder assisted modulator. More explicitly, the proposed VL-STCM-ID arrangement is a jointly designed iteratively decoded scheme combining source coding, channel coding, modulation as well as spatial diversity/multiplexing. As expected, the higher the source correlation, the higher the achievable performance gain of the scheme becomes. Furthermore, the performance of the VL-STCM-ID scheme is about 14.6 dB better than that of the fixed Length STCM (FL-STCM) benchmarker at a source symbol error ratio of 10-4

J.t.h. Chung-how - One of the best experts on this subject based on the ideXlab platform.

  • ISCAS (4) - Robust image and video coding with pyramid vector quantisation
    ISCAS'99. Proceedings of the 1999 IEEE International Symposium on Circuits and Systems VLSI (Cat. No.99CH36349), 1999
    Co-Authors: J.t.h. Chung-how, David Bull
    Abstract:

    Most current image and video coding standards use variable Length codes to achieve compression, which renders the compressed bitstream very sensitive to channel errors. In this paper, image and video coders based on Pyramid Vector Quantisation (PVQ) and using only fixed Length codes are proposed. Still image coders using PVQ in conjunction with DCT and wavelet techniques are described and their robustness to random channel errors are investigated. This work is then extended to video coding. A novel fixed rate motion compensated wavelet/PVQ video coder suitable for low bit-rate applications and generating only fixed Length Codewords is presented. Its compression performance and robustness to random bit errors is compared with H.263.

  • Robust image and video coding with pyramid vector quantisation
    1999 IEEE International Symposium on Circuits and Systems (ISCAS), 1999
    Co-Authors: J.t.h. Chung-how
    Abstract:

    Most current image and video coding standards use variable Length codes to achieve compression, which renders the compressed bitstream very sensitive to channel errors. In this paper, image and video coders based on Pyramid Vector Quantisation (PVQ) and using only fixed Length codes are proposed. Still image coders using PVQ in conjunction with DCT and wavelet techniques are described and their robustness to random channel errors are investigated. This work is then extended to video coding. A novel fixed rate motion compensated wavelet/PVQ video coder suitable for low bit-rate applications and generating only fixed Length Codewords is presented. Its compression performance and robustness to random bit errors is compared with H.263.